Abstract
In this papaer, two preventive maintenance policies, namely, Policy [I] and Policy[II], are proposed for a series system composed of the two subsystems from which the critical and minor failures occur respectively. In Policy[I], the preventive maintenance for the critical failure and the corrective maintenance for the minor one are taken separately. In Policy[II], the preventive maintenance for the critical failure is executed together with the k-th corrective maintenance of the minor one counting from the last maintenance for the critical one. The existence of the optimal solution in Policy[I]and the approximate solution in Policy[II]are presented. The results of the numerical analyses show that Policy[II]considering the scaleeconomy is better than Policy[I]in some circumstances.
